Electric double-layer capacitor having a laminated overcoat

Abstract

An electric double-layer capacitor (EDLC) has a laminated overcoat encapsulating a stacked body including a plurality of basic cells and a pair of terminals sandwiching therebetween the stacked body. The innermost film of the laminated overcoat is thermally fused onto the exposed surfaces of the terminal plates and the stacked body substantially without a gap. The fusing step is conducted by an equal-pressure pressing using a hot water while the internal of the laminated overcoat is evacuated.

What is claimed is:  
     
       1. An electric double-layer capacitor (EDLC) comprising: 
       a stacked body including at least one basic cell having  
       a separator,  
       a pair of polarized electrodes sandwiching therebetween said separator,  
       a pair of current collectors sandwiching therebetween said pair of polarized electrodes,  
       said separator and said polarized electrodes being impregnated with an electrolytic solution;  
       a pair of terminal plates sandwiching therebetween said stacked body, said terminal plates being electrically connected to said current collectors disposed on outermost sides of said stacked body;  
       a pair of external terminals extending from said terminal plates; and  
       a laminated overcoat encapsulating said stacked body and said terminal plates, said laminated overcoat having an innermost film adhered to substantially entire exposed surfaces of said terminal plates and of said stacked body.  
     
     
       2. The EDLC as defined in  claim 1 , wherein said innermost film is substantially fused. 
     
     
       3. The EDLC as defined in  claim 1 , wherein said innermost film is made of at least one material selected from the group consisting of polyethylene resin, ethylene copolymer resin and polypropylene. 
     
     
       4. The EDLC as defined in  claim 1 , wherein said laminated overcoat encapsulates said terminal plates and said stacked body on a substrate. 
     
     
       5. The EDLC as defined in  claim 4 , wherein said substrate is a rigid plate or a flexible plate. 
     
     
       6. The EDLC as defined in  claim 4 , wherein said substrate has a plurality of holes for mounting said EDLC. 
     
     
       7. The EDLC as defined in  claim 4 , wherein said substrate has electric terminals or electric wires electrically connected to said terminal plates. 
     
     
       8. The EDLC as defined in  claim 1 , wherein said at least one basic cell includes a plurality of basic cells, and one of said current collectors sandwiched between said polarized electrodes of adjacent two of said basic cells is shared by said adjacent two of said basic cells. 
     
     
       9. The EDLC as defined in  claim 1 , wherein said laminated overcoat is in contact with said pair of terminal plates and said stacked body substantially without forming therebetween a gap. 
     
     
       10. The EDLC as defined in  claim 1 , wherein said laminated overcoat is in contact with said pair of terminal plates and said stacked body such that there is no gap having an inner volume above 0.125 mm 3 . 
     
     
       11. The EDLC as defined in  claim 1 , wherein said laminated overcoat comprises said inner most film, an intermediate foil and an outermost resin layer. 
     
     
       12. The EDLC as defined in  claim 11 , wherein said foil is made from aluminum or aluminum alloy. 
     
     
       13. A method for fabricating the EDLC claimed in  claim 1 , said method comprising the steps of: 
       adhering said innermost film to said exposed surfaces by an equal-pressure pressing technique using a fluid at a temperature higher than a softening temperature of said innermost film.  
     
     
       14. The method as defined in  claim 13 , wherein said innermost film is made of at least one material selected from the group consisting of polyethylene resin, ethylene copolymer resin and polypropylene, and has a thickness of 100 μm or more. 
     
     
       15. The method as defined in  claim 13 , further comprising the step of shaping said laminated overcoat, said stacked body and said terminal plates into a bulk-like body, before said equal-pressure pressing. 
     
     
       16. The method as defined in  claim 13 , wherein the equal-pressure pressing is conducted while an internal of a bag accomodating said laminated overcoat, said terminal plates and said stacked body is evacuated.